It works well in Confluence 2.10.3.

When importing a snipsnap data, Confluence complains the Space ID has already exist in the database:

Caused by: net.sf.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: 2359302, of class: com.atlassian.confluence.spaces.Space

Of course the space id has already exist in the database because space id 2359302 is the destination space where we want to save the Snip Snap data.

The work around is to import your snipsnap data to Confluence 2.10.3 then upgrade the instance to Confluence 3.0.x.